This invention pertains generally to guidance systems for cannon-launched projectiles, and particularly to mechanisms for protecting such a guidance system from the effects of high acceleration and deceleration during a launching phase.
It is known in the art that any guidance system intended to be used in a cannon-launched projectile must be capable of withstanding extremely large forces due to acceleration (and deceleration) experienced during the launching phase of such a projectile. For example, in the case of a projectile launched from a 155 millimeter cannon, an initial acceleration caused by firing results in a setback load in the order of 12,000 G (where G is the mass of the seeker) and then a deceleration (experienced when the projectile clears the barrel of the cannon) results in a setforward load in the order of 3000 G.
A so-called "strap-down" seeker presently is known to be a practical type of seeker capable of withstanding the setback and setforward loads experienced during the launching phase of a projectile fired from a cannon such as a 155 millimeter cannon. A "strap-down" seeker is characterized by the fact that the sensor in such a seeker is rigidly mounted within a projectile. As a result, a fixed field of view (relative to the centerline of the projectile) is provided. Consequently, unpredictable perturbations in the attitude of the projectile, i.e., coning due to precession or to nutation of the centerline of the projectile, cause the field of view similarly to change in an unpredictable manner. As a result, then, tracking of a desired target may become impossible.